The new National Stadium, now under construction in Tokyo's Shinjuku Ward, is pictured in this May 12, 2017 file photo. (Mainichi)

The parents of a man involved in 2020 Tokyo Olympic and Paralympic construction work who killed himself have applied for workers' compensation, claiming his suicide was induced by excessive overtime, it has been learned.

The application, which was sent to the Ueno Labor Standards Inspection Office in Tokyo, was announced by the parents' lawyer, Hiroshi Kawahito, at a July 20 press conference.

The parents claim that their 23-year-old son took his own life after developing a mental illness caused by working just under 200 hours of monthly overtime. According to Kawahito, the man's entry and exit records at the building site for the 2020 Games' main venue, the new National Stadium, show that he clocked up about 94 hours of overtime in December 2016, some 142.5 hours in January 2017, and around 196 hours in February 2017. All these figures exceed the so-called "death due to overwork" danger line of 80 hours of overtime per month. The records also indicate that the man worked through the night on three occasions in February.

After graduating from university, the man joined a civil engineering company in Tokyo in April 2016, and was put in charge of foundation improvement at the new National Stadium in mid-December. However, on March 2, 2017, he went missing after telling his office over the phone, "I won't be coming in today."

A month later, on April 15, his body was found in Nagano Prefecture. A suicide note found near his body stated, "As a person who has reached his mental and physical limit, this is the only conclusion that I can think of. To my family, friends and coworkers, I am genuinely sorry." Nagano Prefectural Police are apparently treating the death as suicide.

According to a testimony by the man's mother, he would often wake up at 4:30 a.m. and return home at about 1 a.m. It is understood that he once told his parents, "The machinery is not in good condition, and the schedule has become very tight." In addition, Kawahito points out, "There was pressure at the site to ensure that the project be completed in time for Tokyo 2020."

In interviews with the Mainichi Shimbun, the man's former employer stated, "To the bereaved relatives, we are deeply sorry, and we are treating the incident seriously." Meanwhile, Taisei Corp., the chief contractor, has said, "We will instruct specialist construction firms to which we subcontract work, to comply with any applicable laws as carefully as possible."

Regarding the new National Stadium, the original plan was criticized for swelling costs and scrapped in July 2015. As a result, construction did not commence until December last year, about 14 months behind schedule. The Japan Sport Council (JSC), which tendered the building contract, then demanded that the project be completed at a faster pace.

On July 20, Kawahito sent a written request to Tokyo Olympics organizing committee President Yoshiro Mori, demanding that excessive overtime be addressed.

"People's lives and health must not be ruined during the preparations for the 2020 Games. The fact that it is a national event is no excuse whatsoever," Kawahito adds.

Looking ahead, the lawyer said he also plans to send a similar request to Tokyo Gov. Yuriko Koike, the minister in charge of the Games, Tamayo Marukawa, and to the JSC.